[gmx-users] g_cluster[output]

[Osmany Guirola Cruz]

Hi
  I am doing cluster analysis of my simulation. I use gromos method, and 
analyse the backbone, but i need that the output(clusters.pdb) was the entire 
peptide. First time i did this
  group for least squares fit       4(backbone)
  group for output                      4(backbone)
and i found 4 clusters.
next time i did this 
   group for least squares fit       4(backbone)
  group for output                     1(protein) (this is really that i need)
and i found 15 clusters 
WHY? i just change "group for output"  i think that the result must be the 
same(i don't change the trajectory files) 
What can i do?